feat: Improve Report API performance (#9476)

- Re-write the methods for clarity
- Remove the dependency on the ReportHelper class.
- Remove n+1 queries in the average metric time series data.

app/builders/v2/reports/conversations/base_report_builder.rb

@@ -0,0 +1,30 @@
+class V2::Reports::Conversations::BaseReportBuilder
+  pattr_initialize :account, :params
+
+  private
+
+  AVG_METRICS = %w[avg_first_response_time avg_resolution_time reply_time].freeze
+  COUNT_METRICS = %w[
+    conversations_count
+    incoming_messages_count
+    outgoing_messages_count
+    resolutions_count
+    bot_resolutions_count
+    bot_handoffs_count
+  ].freeze
+
+  def builder_class(metric)
+    case metric
+    when *AVG_METRICS
+      V2::Reports::Timeseries::AverageReportBuilder
+    when *COUNT_METRICS
+      V2::Reports::Timeseries::CountReportBuilder
+    end
+  end
+
+  def log_invalid_metric
+    Rails.logger.error "ReportBuilder: Invalid metric - #{params[:metric]}"
+
+    {}
+  end
+end

app/builders/v2/reports/conversations/metric_builder.rb

@@ -0,0 +1,30 @@
+class V2::Reports::Conversations::MetricBuilder < V2::Reports::Conversations::BaseReportBuilder
+  def summary
+    {
+      conversations_count: count('conversations_count'),
+      incoming_messages_count: count('incoming_messages_count'),
+      outgoing_messages_count: count('outgoing_messages_count'),
+      avg_first_response_time: count('avg_first_response_time'),
+      avg_resolution_time: count('avg_resolution_time'),
+      resolutions_count: count('resolutions_count'),
+      reply_time: count('reply_time')
+    }
+  end
+
+  def bot_summary
+    {
+      bot_resolutions_count: count('bot_resolutions_count'),
+      bot_handoffs_count: count('bot_handoffs_count')
+    }
+  end
+
+  private
+
+  def count(metric)
+    builder_class(metric).new(account, builder_params(metric)).aggregate_value
+  end
+
+  def builder_params(metric)
+    params.merge({ metric: metric })
+  end
+end

app/builders/v2/reports/conversations/report_builder.rb

@@ -0,0 +1,21 @@
+class V2::Reports::Conversations::ReportBuilder < V2::Reports::Conversations::BaseReportBuilder
+  def timeseries
+    perform_action(:timeseries)
+  end
+
+  def aggregate_value
+    perform_action(:aggregate_value)
+  end
+
+  private
+
+  def perform_action(method_name)
+    return builder.new(account, params).public_send(method_name) if builder.present?
+
+    log_invalid_metric
+  end
+
+  def builder
+    builder_class(params[:metric])
+  end
+end

app/builders/v2/reports/timeseries/average_report_builder.rb

@@ -0,0 +1,48 @@
+class V2::Reports::Timeseries::AverageReportBuilder < V2::Reports::Timeseries::BaseTimeseriesBuilder
+  def timeseries
+    grouped_average_time = reporting_events.average(average_value_key)
+    grouped_event_count = reporting_events.count
+    grouped_average_time.each_with_object([]) do |element, arr|
+      event_date, average_time = element
+      arr << {
+        value: average_time,
+        timestamp: event_date.in_time_zone(timezone).to_i,
+        count: grouped_event_count[event_date]
+      }
+    end
+  end
+
+  def aggregate_value
+    object_scope.average(average_value_key)
+  end
+
+  private
+
+  def event_name
+    metric_to_event_name = {
+      avg_first_response_time: :first_response,
+      avg_resolution_time: :conversation_resolved,
+      reply_time: :reply_time
+    }
+    metric_to_event_name[params[:metric].to_sym]
+  end
+
+  def object_scope
+    scope.reporting_events.where(name: event_name, created_at: range)
+  end
+
+  def reporting_events
+    @grouped_values = object_scope.group_by_period(
+      group_by,
+      :created_at,
+      default_value: 0,
+      range: range,
+      permit: %w[day week month year hour],
+      time_zone: timezone
+    )
+  end
+
+  def average_value_key
+    @average_value_key ||= params[:business_hours].present? ? :value_in_business_hours : :value
+  end
+end

app/builders/v2/reports/timeseries/base_timeseries_builder.rb

@@ -0,0 +1,46 @@
+class V2::Reports::Timeseries::BaseTimeseriesBuilder
+  include TimezoneHelper
+  include DateRangeHelper
+  DEFAULT_GROUP_BY = 'day'.freeze
+
+  pattr_initialize :account, :params
+
+  def scope
+    case params[:type].to_sym
+    when :account
+      account
+    when :inbox
+      inbox
+    when :agent
+      user
+    when :label
+      label
+    when :team
+      team
+    end
+  end
+
+  def inbox
+    @inbox ||= account.inboxes.find(params[:id])
+  end
+
+  def user
+    @user ||= account.users.find(params[:id])
+  end
+
+  def label
+    @label ||= account.labels.find(params[:id])
+  end
+
+  def team
+    @team ||= account.teams.find(params[:id])
+  end
+
+  def group_by
+    @group_by ||= %w[day week month year hour].include?(params[:group_by]) ? params[:group_by] : DEFAULT_GROUP_BY
+  end
+
+  def timezone
+    @timezone ||= timezone_name_from_offset(params[:timezone_offset])
+  end
+end

app/builders/v2/reports/timeseries/count_report_builder.rb

@@ -0,0 +1,71 @@
+class V2::Reports::Timeseries::CountReportBuilder < V2::Reports::Timeseries::BaseTimeseriesBuilder
+  def timeseries
+    grouped_count.each_with_object([]) do |element, arr|
+      event_date, event_count = element
+
+      # The `event_date` is in Date format (without time), such as "Wed, 15 May 2024".
+      # We need a timestamp for the start of the day. However, we can't use `event_date.to_time.to_i`
+      # because it converts the date to 12:00 AM server timezone.
+      # The desired output should be 12:00 AM in the specified timezone.
+      arr << { value: event_count, timestamp: event_date.in_time_zone(timezone).to_i }
+    end
+  end
+
+  def aggregate_value
+    object_scope.count
+  end
+
+  private
+
+  def metric
+    @metric ||= params[:metric]
+  end
+
+  def object_scope
+    send("scope_for_#{metric}")
+  end
+
+  def scope_for_conversations_count
+    scope.conversations.where(account_id: account.id, created_at: range)
+  end
+
+  def scope_for_incoming_messages_count
+    scope.messages.where(account_id: account.id, created_at: range).incoming.unscope(:order)
+  end
+
+  def scope_for_outgoing_messages_count
+    scope.messages.where(account_id: account.id, created_at: range).outgoing.unscope(:order)
+  end
+
+  def scope_for_resolutions_count
+    scope.reporting_events.joins(:conversation).select(:conversation_id).where(
+      name: :conversation_resolved,
+      conversations: { status: :resolved }, created_at: range
+    ).distinct
+  end
+
+  def scope_for_bot_resolutions_count
+    scope.reporting_events.joins(:conversation).select(:conversation_id).where(
+      name: :conversation_bot_resolved,
+      conversations: { status: :resolved }, created_at: range
+    ).distinct
+  end
+
+  def scope_for_bot_handoffs_count
+    scope.reporting_events.joins(:conversation).select(:conversation_id).where(
+      name: :conversation_bot_handoff,
+      created_at: range
+    ).distinct
+  end
+
+  def grouped_count
+    @grouped_values = object_scope.group_by_period(
+      group_by,
+      :created_at,
+      default_value: 0,
+      range: range,
+      permit: %w[day week month year hour],
+      time_zone: timezone
+    ).count
+  end
+end

app/controllers/api/v2/accounts/reports_controller.rb

@@ -5,19 +5,17 @@ class Api::V2::Accounts::ReportsController < Api::V1::Accounts::BaseController
   before_action :check_authorization
 
   def index
-    builder = V2::ReportBuilder.new(Current.account, report_params)
-    data = builder.build
+    builder = V2::Reports::Conversations::ReportBuilder.new(Current.account, report_params)
+    data = builder.timeseries
     render json: data
   end
 
   def summary
-    render json: summary_metrics
+    render json: build_summary(:summary)
   end
 
   def bot_summary
-    summary = V2::ReportBuilder.new(Current.account, current_summary_params).bot_summary
-    summary[:previous] = V2::ReportBuilder.new(Current.account, previous_summary_params).bot_summary
-    render json: summary
+    render json: build_summary(:bot_summary)
   end
 
   def agents
@@ -126,10 +124,11 @@ class Api::V2::Accounts::ReportsController < Api::V1::Accounts::BaseController
     }
   end
 
-  def summary_metrics
-    summary = V2::ReportBuilder.new(Current.account, current_summary_params).summary
-    summary[:previous] = V2::ReportBuilder.new(Current.account, previous_summary_params).summary
-    summary
+  def build_summary(method)
+    builder = V2::Reports::Conversations::MetricBuilder
+    current_summary = builder.new(Current.account, current_summary_params).send(method)
+    previous_summary = builder.new(Current.account, previous_summary_params).send(method)
+    current_summary.merge(previous: previous_summary)
   end
 
   def conversation_metrics

app/helpers/timezone_helper.rb

@@ -0,0 +1,19 @@
+module TimezoneHelper
+  # ActiveSupport TimeZone is not aware of the current time, so ActiveSupport::Timezone[offset]
+  # would return the timezone without considering day light savings. To get the correct timezone,
+  # this method uses zone.now.utc_offset for comparison as referenced in the issues below
+  #
+  # https://github.com/rails/rails/pull/22243
+  # https://github.com/rails/rails/issues/21501
+  # https://github.com/rails/rails/issues/7297
+  def timezone_name_from_offset(offset)
+    return 'UTC' if offset.blank?
+
+    offset_in_seconds = offset.to_f * 3600
+    matching_zone = ActiveSupport::TimeZone.all.find do |zone|
+      zone.now.utc_offset == offset_in_seconds
+    end
+
+    return matching_zone.name if matching_zone
+  end
+end